Why do you recommend against cardio with the X3?Updated a month ago

Most people who engage in “cardio” exercise do so to reduce their body fat. However, this may be one of the worst approaches to achieving that goal because cardiovascular exercise up-regulates cortisol.

This has an impact that runs counter to what these fitness enthusiasts want. Cortisol reduces muscle mass and protects body fat, so you keep that fat in your body as a backup energy supply for as long as possible. Your body adapts to its environment, and endurance exercise signals that the body needs a substantial energy supply available at all times.

The use of X3, on the other hand, does not increase cortisol as cardio does. Instead, X3 upregulates growth hormone, which can increase tendon and ligament repair, accelerate body fat loss, and increase general fitness levels.

Some people also engage in cardio because they want to promote cardiovascular health. It’s not well publicized, but research has repeatedly shown that strength training promotes the same or greater changes in cardio-related health metrics. This is discussed at length in our book, Weight Lifting is a Waste of Time.

Related research on endurance cardio exercise

Cortisol is upregulated in endurance exercise. This sacrifices muscle in favor of protecting body fat. Schwarz, L., & Kindermann, W. (1989). β-Endorphin, catecholamines, and cortisol during exhaustive endurance exercise. International journal of sports medicine, 10(05), 324-328.

Higher cortisol levels are associated with muscle loss.

Peeters, G. M. E. E., Van Schoor, N. M., Van Rossum, E. F. C., Visser, M., & Lips, P. T. A. M. (2008). The relationship between cortisol, muscle mass, and muscle strength in older persons and the role of genetic variations in the glucocorticoid receptor. Clinical endocrinology, 69(4), 673-682.

Higher cortisol levels contribute to faster and longer-lasting body fat storage.

Moyer, A. E., Rodin, J., Grilo, C. M., Cummings, N., Larson, L. M., & Rebuffé‐Scrive, M. (1994). Stress‐induced cortisol response and fat distribution in women. Obesity Research, 2(3), 255-262.

Meta-analysis

Over 100 studies analyzed (known as a meta-analysis) show that brief, high-intensity interval training increases endurance as much as or more than traditional endurance training. Importantly, duration appears to be less important than intensity. These data suggest that resistance training's shorter duration and higher intensity may give it an advantage over intervals in building cardiovascular fitness.

Steele, J., Fisher, J., & Bruce-Low, S. (2012). Resistance training to momentary muscular failure improves cardiovascular fitness in humans: a review of acute physiological responses and chronic physiological adaptations. Journal of Exercise Physiology Online, 15(3), 53-80.